In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Among non - users of aspirin , the adjusted hazard ratios ( 95 % confidence interval ) of hospitalization for AMI / GI vs the acetaminophen ( with no aspirin ) group were : rofecoxib 1 . 27 ( 1 . 13 , 1 . 42 ) , celecoxib 0 . 93 ( 0 . 83 , 1 . 03 ) , naproxen 1 . 59 ( 1 . 31 , 1 . 93 ) , diclofenac 1 . 17 ( 0 . 99 , 1 . 38 ) and ibuprofen 1 . 05 ( 0 . 74 , 1 . 51 ) .
### Output Text:
Among non - users of <span class="chemical">aspirin</span> , the adjusted hazard ratios ( 95 % confidence interval ) of hospitalization for AMI / GI vs the <span class="chemical">acetaminophen</span> ( with no <span class="chemical">aspirin</span> ) group were : <span class="chemical">rofecoxib</span> 1 . 27 ( 1 . 13 , 1 . 42 ) , <span class="chemical">celecoxib</span> 0 . 93 ( 0 . 83 , 1 . 03 ) , <span class="chemical">naproxen</span> 1 . 59 ( 1 . 31 , 1 . 93 ) , <span class="chemical">diclofenac</span> 1 . 17 ( 0 . 99 , 1 . 38 ) and <span class="chemical">ibuprofen</span> 1 . 05 ( 0 . 74 , 1 . 51 ) . 