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: Current estimates suggest that between 0 . 4 % and 8 . 3 % of children and adolescents are affected by major depression .
### Output Text:
Current estimates suggest that between 0 . 4 % and 8 . 3 % of children and adolescents are affected by major depression . 