Katy Perry     /n  {img}8.jpg{/img}  /n     ,            "Billboard".  /n         "Last Friday Night"       ,    .  /n  ,   ,    1987-88 ,             "Bad".  /n    50-  - "Billboard"         ,    .  /n   -"California Gurls", "Teenage Dream", "Firework", "E.T."  "Last Friday Night"-       "Teenage Dreams".  /n      2010        ,    ,         ,  2,2  .  /n        ,     25%      .   ,        . /n 
