Lead analyst Gene Munster also estimates that the Mac user base is now about 23 miillion, saying "From a high level, these numbers show that the Mac user base is growing. It also shows that it is an unusually active use base, with 9% of the ~23m users upgrading in just the first four days." Compared to the Windows user base, Munster said, these numbers demonstrate the Mac's strong brand loyalty, and Apple's ability to sell more frequent operating system upgrades to a larger percentage of its user base. Piper Jaffray has reiterated its outperform rating on shares of Apple Inc..