The average lifespan of domestic cats has increased in recent decades. It has risen from seven years in the 1980s, to nine years in 1995, to about 15 years in 2021. Reliable information on the lifespans of domestic cats is varied and limited.[2] Nevertheless, a number of studies have investigated the matter and have come up with noteworthy estimates. Estimates of mean lifespan in these studies range between 13 and 20 years, with a single value in the neighborhood of 15 years.[3][4][5] At least one study found a median lifespan value of 14 years and a corresponding interquartile range of 9 to 17 years.[6] Maximum lifespan has been estimated at values ranging from 22 to 30 years although there have been claims of cats living longer than 30 years.[2][3][6][7][8][9] According to the 2010 edition of the Guinness World Records, the oldest cat ever recorded was Creme Puff, who died in 2005, aged 38 years, 3 days.[10] Female cats typically outlive male cats, and crossbred cats typically outlive purebred cats. It has also been found that the greater a cat's weight, the lower its life expectancy on average.[6] A common misconception in cat aging (and dog aging) is that a cat ages the equivalent of what a human would age in seven years each year. This is inaccurate due to the inconsistencies in aging as well as there being far more accurate equations to predict a cat's age in "cat years". A more accurate equation often used by veterinarians to predict cat years is 4x + 16, (x being the chronological age of the cat) which works for cats who are two years of age or older.[citation needed] In one study of cat mortality, the most frequent causes were trauma (12.2%), renal disorder (12.1%), non-specific illness (11.2%), neoplasia (10.8%) and mass lesion disorders (10.2%).