I cant find that summary anywhere there, so I googled around.
Here's govtrack.com
If you check the numbers, you see that most of the votes he missed was during the 2000 campaign, and this campaign.John McCain missed 738 of 4104 roll call votes (18%) since Feb 4, 1993.
Here's Obamas numbers
So, Obama has missed 306 votes in less than 4 years, while McCain has missed 738 votes in over 15 years.Barack Obama missed 306 of 1287 roll call votes (24%) since Jan 6, 2005.
Also note that there are a lot more roll call votes in later years, and there weren't as many in the 1990s, so the numbers are scewed in Obamas favor. If there had been as many roll calls in McCains early years, McCains numbers would probably have been something like 800/5500 = 15% missed roll call votes.