NO. The study is flawed because ACTIVE Mormons were questioned. Perhaps close to 85 or 90 percent of them tithe. However, since less than half of Mormons are active, the real percentage of LDS people who tithe is, I would guess, about 40.
I ran across the list of tithe payers when my husband was bishop and not even close to 90% were paying tithing (I couldn't help myself, I was no longer a believer and extremely curious). I would say around 30-40 families claimed to be full tithe payers in the entire ward. A few very active members were not paying tithing. Even at that a lot of tithing money was collected, over $300,000.
I can tell you for a fact that in my old ward and stake the numbers were close to 15% full tithe payers, and 25% max of the stake paid some sort of tithe. They skew the numbers to make you feel like the minority so you want to fit in and pay tithe.