The average American watches somewhere around 5 hours of TV per day (although that figure varies quite dramatically by age), and roughly one-quarter of that programming is advertising, details Nielsen in its latest annual “Advertising and Audiences” report [download page], timed for the Upfront season. In fact, commercial clutter has been gradually increasing on network TV, where 14-and-a-quarter minutes of commercial aired during each hour of programming last year, up by almost one minute from 2009 (13:25).

Ad loads on cable are even larger – and have grown even more quickly over the past 5 years. Last year, 15 minutes and 38 seconds of commercials aired on average per hour of cable TV programming, up from 14 minutes and 27 seconds in 2009, though down from a peak of 16 minutes and 11 seconds in 2011.

(The article’s headline says “exposed” to ads – because there’s a good debate to be had about how many of these ads are being watched, particularly as multitasking continues to be popular.)

Meanwhile, TV ad spending continues to rise, growing by 3% year-over-year last year (its slowest rate since at least 2010) to reach $78 billion. Why the rise in spending? Aside from increasing ad loads, TV ads continue to have an immense influence on consumers’ purchase decisions, as seen in this detailed MarketingCharts analysis of the US TV ad market.

Interestingly, though, the average cost of a primetime 30-second TV spot (broadcast and cable) has been steadily dropping over the years, down to roughly $7,800 last year from $8,900 in 2009. That may be the result of shifts in viewing behavior, though the Nielsen report doesn’t outline any trends with regards to primetime audiences. It does reveal a shift in primetime viewing habits by day of the week: Sunday boasts the largest primetime audience for the 2013-2014 season-to-date, with an average of 125 million persons with sets in use.

Returning to commercials, the report indicates that 30-second spots are becoming less prominent choices for advertisers. Last year, they accounted for 53% of commercials aired – down from 62% in 2000. By contrast, the 15-second spot has become increasingly popular, growing to 44% share of commercials aired, from 35% in 2000. Nielsen notes that “95 percent of neuro-optimized, shortened ads performed as well as or better than their original :30 counterparts.”

Nielsen recently reported that the overall number of TV households in the US grew by 0.4% last year to 116.3 million. The number of TV homes has grown in the past decade among African-American households (13.2 million to 14.9 million), Hispanic households (10.9 million to 14.7 million) and Asian-American households (4.1 million to 5.2 million).

Even so, Whites account for 71.3% share of primetime TV usage for the season-to-date, versus 14.5% for African-Americans and 3.4% for Asian-Americans. And Hispanics account for 14.2% share of primetime usage, such that they under-index relative to their share of the population.