THREE large open medical schemes have announced their contribution increases for next year, with average increases on two schemes coming in at just below 10 percent and the third coming in at more than 13 percent. Last year, medical schemes implemented increases that averaged about 6.2 percent, while claims that schemes paid on behalf of members rose by 12 percent. Schemes say the trend of contribution income not keeping pace with increases in claims has continued this year, making higher contribution increases necessary.