That's the report card for the current Congress. Note that Senators Obama and Clinton (we could hardly say they aren't committed on abortion!) also missed several votes. That's because they're running for President. On that report card, only presidential candidates (including Joe Biden) and the injured Tim Johnson missed more than one vote. But take a look at this score card...
http://www.populationconnection.org/Reports_Publications/Reports/dl/455 where McCain voted against all but one item a bunch of population control weirdos wanted, and these NRLC 108th and 109th Congress report cards, where he's in on every vote and he gets an 81% and 75% respectively. In fact, I think he should have gotten a 100% for the 108th, because the two votes where he disagrees with the NRLC are Medicare funding issues. BTW, note the ratings that Obama and Hilllary got on those report cards: 100% from the population control freaks and 0% from the NRLC. Note especially that they voted against Roberts and Alito and McCain voted for them.
McCain sure has his flaws, but on the pro-life issue the choice this year is between good and absolutely abyssmal.