What year's are you looking for? I still use Frohike's parkdat files that he created for OOTP3 that have accurate park factors year-to-year and have gradually been updating them year-by-year as I come to the year. Trouble of course was that I never was able to get past 1930 with OOTP4
I have 1901 thru 1935 updated and certain years past 1985 that I have updated. If you are looking for a specific year I could probably quick update it and post it here.