PMC full text: | Published online 2014 Nov 18. doi: 10.1186/s12998-014-0035-6
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Table 1
First survey year → | Second survey year → | Third survey year → |
---|---|---|
Grade 0 | Grade 1 | Grade 2 |
Grade 1 | Grade 2 | Grade 3 |
Grade 2 | Grade 3 | Grade 4 |
Grade 3 | Grade 4 | Grade 5 |
Grade 4 | Grade 5 | Grade 6 |