Bummed out by your property tax bill this year? Bill Gates may be too, although he can assuage himself by filling one of his rows of bathtubs with C-notes and diving in. Taxes on Gates’ Medina mega-mansion have jumped to $1,063,602.24 this year, according to the King County Asessor’s office. That’s an increase of $51,000 over last year, and almost $85,000 since 2006.But of course his property values shot up too – the 48,000-square-foot, four-level house-as-resort, spread along Lake Washington on a 224,000-square-foot lot, is now assessed at $147.5 million; it came in at $125 million two years ago. Since he built “Xanadu 2.0” essentially in 1994 when it was valued around $50 million, Gates has added property and structures including a delivery entrance that looks like the entryway of a national park.But it’s less expansion and mostly rising property values that have pushed up the numbers in recent years. After all, for Gates, wife Melinda and children Jennifer, Rory and Phoebe, they’ve probably got all the bedrooms (8) and bathrooms (25) they need.