Despite a healthy economy and booming real estate market, 2.2% of Orange County mortgages were “seriously underwater” at year’s end, Attom Data Solutions says.

Orange County had 12,854 underwater homes in last year’s fourth quarter, said Attom, which tracked what it sees as some of the most troublesome home loans: mortgages that are 25% greater (or more) than the value of the home. While this may sound like a lot of troubled loans, Orange County’s share of seriously underwater mortgages was 10th lowest among the 50 most-populated U.S. counties.

Underwater loans are seen as being at a high risk of default. If the economy sours or if the owner’s finances get stretched, there’s little financial motivation keeping the borrower in these homes. Challenges that “underwater” stats highlight are lingering value issues from the bubble bursting a decade ago as well as more recently reduced values of high-end housing.

California had 189,896 seriously underwater home loans in the fourth quarter. That’s 2.7% of all mortgaged properties, third-lowest nationwide. By the way, 7% of mortgages in the rest of the U.S. are seriously underwater by Attom’s math.

If you look at the Orange County results at the neighborhood level, the pricier the community — think coastal towns or fancy foothill areas — the more likely the chance for badly underwater homes. Shortages of affordable residences have kept low-end prices stronger than the bulk of the market. Plus, cheaper homes are often bought with large down payments or in all-cash deals, creating high levels of equity.

Look at the number and share of seriously underwater mortgages in big Orange County ZIPs and how that percentage ranked among 979 California ZIPs tracked by Attom. Let’s start with the 10 Orange County ZIPs with the highest level of problem loans …

1. Laguna Beach 92651: 410 mortgages or 6.01% of all home loans — ranking No. 918 statewide.

2. Newport Coast 92657: 148 or 5.71% — No. 911 statewide.

3. Newport Beach 92663: 236 or 5.39% — No. 894 statewide.

4. Corona Del Mar 92625: 177 or 5.27% — No. 885 statewide.

5. Tustin 92782: 251 or 3.67% — No. 792 statewide.

6. Laguna Hills 92637: 87 or 3.56% — No. 776 statewide.

7. Trabuco Canyon 92679: 296 or 3.10% — No. 695 statewide.

8. Newport Beach 92660: 229 or 3.06% — No. 682 statewide.

9. San Clemente 92673: 238 or 2.97% — No. 664 statewide.

10. San Juan Capistrano 92675: 235 or 2.93% — No. 653 statewide.

Now, let’s countdown to the ZIP with the fewest underwater loans …

10. Anaheim 92804: 152 or 1.44% — No. 199 statewide.

9. Santa Ana 92703: 78 or 1.40% — No. 182 statewide.

8. Santa Ana 92707: 105 or 1.40% — No. 181 statewide.

7. Santa Ana 92706: 68 or 1.37% — No. 177 statewide.

6. Garden Grove 92840: 111 or 1.33% — No. 166 statewide.

5. Garden Grove 92843: 74 or 1.33% — No. 164 statewide.

4. Anaheim 92806: 61 or 1.32% — No. 161 statewide.

3. Garden Grove 92845: 56 or 1.25% — No. 142 statewide.

2. Huntington Beach 92647: 115 or 1.24% — No. 135 statewide.

1. Garden Grove 92841: 57 or 1.18% — No. 125 statewide.

Finally, the rest of Orange County tracked by Attom …

Costa Mesa 92626: 229 or 2.82% — No. 638 statewide.

Irvine 92603: 130 or 2.80% — No. 635 statewide.

Dana Point 92629: 201 or 2.77% — No. 633 statewide.

Huntington Beach 92648: 272 or 2.75% — No. 627 statewide.

Fullerton 92835: 159 or 2.71% — No. 617 statewide.

San Clemente 92672: 207 or 2.64% — No. 597 statewide.

Mission Viejo 92692: 349 or 2.63% — No. 596 statewide.

Irvine 92602: 125 or 2.55% — No. 577 statewide.

Fullerton 92832: 81 or 2.55% — No. 575 statewide.

Costa Mesa 92627: 197 or 2.49% — No. 561 statewide.

Irvine 92618: 142 or 2.44% — No. 544 statewide.

Laguna Hills 92653: 174 or 2.44% — No. 541 statewide.

Anaheim 92807: 234 or 2.40% — No. 532 statewide.

Laguna Niguel 92677: 425 or 2.33% — No. 507 statewide.

Fullerton 92833: 231 or 2.32% — No. 506 statewide.

Orange 92869: 209 or 2.32% — No. 504 statewide.

Santa Ana 92705: 196 or 2.26% — No. 481 statewide.

Ladera Ranch 92694: 173 or 2.26% — No. 477 statewide.

Irvine 92612: 103 or 2.23% — No. 469 statewide.

Fullerton 92831: 113 or 2.20% — No. 457 statewide.

Tustin 92780: 170 or 2.20% — No. 454 statewide.

Aliso Viejo 92656: 291 or 2.18% — No. 445 statewide.

Huntington Beach 92649: 179 or 2.14% — No. 432 statewide.

Mission Viejo 92691: 281 or 2.13% — No. 428 statewide.

Irvine 92620: 221 or 2.03% — No. 394 statewide.

Brea 92821: 159 or 1.98% — No. 380 statewide.

Anaheim 92802: 84 or 1.97% — No. 375 statewide.

Lake Forest 92630: 287 or 1.89% — No. 350 statewide.

Orange 92867: 159 or 1.88% — No. 347 statewide.

Placentia 92870: 197 or 1.86% — No. 341 statewide.

Anaheim 92808: 107 or 1.80% — No. 322 statewide.

Garden Grove 92844: 61 or 1.80% — No. 320 statewide.

Irvine 92606: 66 or 1.78% — No. 313 statewide.

Fountain Valley 92708: 225 or 1.77% — No. 310 statewide.

Anaheim 92801: 106 or 1.76% — No. 309 statewide.

Rancho Santa Margarita 92688: 202 or 1.73% — No. 300 statewide.

Westminster 92683: 219 or 1.62% — No. 259 statewide.

Irvine 92614: 85 or 1.60% — No. 250 statewide.

Orange 92865: 67 or 1.58% — No. 246 statewide.

Anaheim 92805: 125 or 1.57% — No. 241 statewide.

Foothill Ranch 92610: 51 or 1.57% — No. 240 statewide.

Orange 92866: 35 or 1.73% — No. 298 statewide.

Huntington Beach 92646: 246 or 1.67% — No. 279 statewide.

Santa Ana 92704: 164 or 1.65% — No. 274 statewide.

Orange 92868: 44 or 1.64% — No. 271 statewide.

Santa Ana 92701: 64 or 1.64% — No. 268 statewide.

Irvine 92604: 95 or 1.46% — No. 207 statewide.