March 2000 June 2016 March 2000 June 2016 March 2000 June 2016 Credit: Donald Miralle/Allsport (left) and Mark J. Terrill/Associated Press (right)

In 2000, Michael Phelps traveled to Sydney, Australia, to swim in his first Olympics. He finished fifth in the 200-meter butterfly final, ahead of three swimmers who were in their 20s. Phelps was 15.

Now 31, Phelps — with a young son in tow and 27 Olympic medals around his neck — has swum in more Olympic events than anyone else in history. That was before his events in Rio this year: if those are included, no one else comes close.

The Rio Games represent his fifth Olympics. By charting all of Phelps’s individual race times since Sydney, including the time that won him gold in the 200-meter Individual Medley on Tuesday, we can see how his performance has changed over the last 16 years:

2008 ’11 2012 ’09 5% Faster ’15 2016 Gold Faster times ’07 ’06 ’03 ’10 ’14 2004 ’05 Silver ’02 ’01 2000 ’13 2016 Olympic Qualifying Times Each line is Phelps’s time in a single race Phelps retired during 2013, and was suspended for a D.U.I. for much of 2015. Slower times Swimmers often swim slower when training for important events. 5% Slower Phelps could do no wrong at the Beijing Olympics: he won gold in all of his events. He is training for Rio with a regimen similar to the one that helped him dominate in Beijing. He is training for Rio with a regimen similar to the one that helped him dominate in Beijing. Phelps could do no wrong at the Beijing Olympics: he won gold in all of his events. Faster times 2008 ’11 2012 ’09 ’15 2016 5% Faster ’07 Gold ’06 ’03 ’10 ’14 2004 Silver ’05 ’02 ’01 2000 2016 Olympic Qualifying Times ’13 Each line is Phelps’s time in a single race Phelps retired during 2013, and was suspended for a D.U.I. for much of 2015. 5% Slower Slower times Swimmers often swim slower when training for important events. 2016 Olympic Qualifying Times 5% Slower 5% Faster 2000 Slower times Faster times ’01 ’02 ’03 Each dot is Phelps’s time in one race ’04 ’05 ’06 ’07 Phelps won gold in all of his events at the Beijing Olympics. ’08 ’09 ’10 ’11 ’12 Gold Silver Phelps retired in 2013, and was suspended for a D.U.I. in 2015. ’13 ’14 ’15 2016 He is training for Rio with a regimen similar to the one that helped him dominate in Beijing. Note: Only individual events are shown; relays are excluded. All swim times are plotted relative to the 2016 Olympics Qualifying Time for respective events. Medals shown in non-Olympic years are for Pan Pacific Championships or World Championships. Data includes most major meets. Source: Swimrankings.net

Most swimmers typically peak around the age of 21, but Phelps swept gold in his events in Beijing at 23. In the leadup to Rio this year, he has posted some times that have approached his fastest ever. In July, he said, “It's been since 2009 since I’ve done a best time, and I think it would be kinda fun to do one before I retire, but time will tell.”

In 2009, many swimmers, including Phelps, had benefitted from the now-illegal hi-tech, buoyant swimsuits. Phelps’s times from 2008 are a more accurate reflection of his personal best.

Phelps did not post a new personal best in Rio, but it wasn’t out of the question. Especially at the beginning of his races, Phelps has matched the speeds that earned him eight gold medals in Beijing. Watch how he has kept pace with his younger self in the early laps of his Olympic races in the 200-meter butterfly:

Although Phelps has remained competitive in shorter races, age has sapped his endurance, and he has lagged behind his younger self after the initial laps of longer events like the 400-meter individual medley, which he won in Beijing and placed fourth in London:

Avoiding grueling races such as the 400 I.M. is one way Phelps aimed to post competitive times in Rio, where his longest race was 200 meters. Instead of trying for gold in a broad mix of events, as he did in 2008, Phelps has now focused his training on shorter events where power is more crucial than endurance.

WC ‘01 PP ‘02 WC ‘03 WC ‘05 PP ‘06 WC ‘07 WC ‘09 PP ‘10 WC ‘11 PP ‘14 Sydney 2000 Athens 2004 Beijing 2008 London 2012 Rio 2016 ‘13 ‘15 100m Butterfly 2ND 2nd 1st 2nd 1st 1st 1st 1st 1st 1st 1st 200m Butterfly 1st 1st 1st 1st 1st 1ST 5th 1st 2nd 1st 1st 1st 2nd 200m Freestyle 1st 1st 3rd 1st 2nd 2nd 200m Medley 1st 1st 1ST 1st 1st 1st 1st 1st 2nd 1st 2nd 400m Medley 1st 1st 1st 1st 1st 1st 4th WC ‘01 PP ‘02 WC ‘03 WC ‘05 PP ‘06 WC ‘07 WC ‘09 PP ‘10 WC ‘11 PP ‘14 Sydney 2000 Athens 2004 Beijing 2008 London 2012 Rio 2016 ‘13 ‘15 100m Butterfly 2ND 2nd 1st 2nd 1st 1st 1st 1st 1st 1st 1st 200m Butterfly 1st 1st 1st 1st 1st 1ST 5th 1st 2nd 1st 1st 1st 2nd 200m Freestyle 1st 1st 3rd 1st 2nd 2nd 200m Medley 1st 1st 1st 1st 1st 1st 1st 1st 2nd 1st 2nd 400m Medley 1st 1st 1st 1st 1st 1st 4th 100m Butterfly 2000 ‘04 ‘08 ‘12 2016 2nd 2nd 1st 2nd 1st 1st 1st 1st 1st 1st 1st 200m Butterfly 1st 1st 1st 1st 1st 1st 5th 1st 2nd 1st 1st 1st 2nd 200m Freestyle 1st 1st 3rd 1st 2nd 2nd 200m Medley 1st 1st 1st 1st 1st 1st 1st 1st 2nd 1st 2nd 400m Medley 1st 1st 1st 1st 1st 1st 4th Note: Medals in non-Olympic years are for the Pan Pacific Championships (PP) or the World Championships (WC). Phelps was retired in 2013, and being punished for a D.U.I. in 2015. Relay races and a 2006 silver medal in the backstroke are not shown.