The most forested nation in all of Europe, 76 percent of Finland’s land area is wooded. Thanks to good management and a focus on sustainability, the forests continue to multiply even when harvested.
Finland's total area is 337,030 km2 (130,128 sq mi)... Of this area 10% is water, 69% forest, 8% cultivated land and 13% other. (Wikipedia, last modified December 26, 2014)
如果對比一下你的數字的話 全國90%為陸地,76% of the land area is wooded 那麼實際的森林面積率大概就是︰ 90% x 76/100 = 68.4% 這樣就得出69%的約值