There was a ~3% delta in absolute ticket sales.
I take it you really mean "so why wasn't 2003 the peak year instead of 2002" to which I'd say "I'm not trying to explain one needs a 55" widescreen 4k TV before you'll ever consider going to the movie theater less often, rather that this kind of difference over time is why you can't say movie theatre ticket sales in 2002 were higher so people must therefore have watched more movies then."