Self storage provider Big Yellow Group saw its annual pre-tax profit rise, with revenue boosted by higher prices and improved occupancy rate.Pre-tax profit for the 12 months to 31 March surged 75.9% year-on-year to £105.2m, while revenue rose 17% to £84.3m FTSE 250-listed Big Yellow said.In a statement released on Tuesday, the group said its occupancy rate rose 4.3% to 73.2% and average net achieved rent per square foot edged 2.6% higher to £24.95.Excluding gains on property assets, operating profit climbed 22.5% to £48.4m, but surged 68.2% £114.2m once the gains were taken into account.Nicholas Vetch, the group executive chairman, said the company was well positioned and would thrive on an improving economy."We have now positioned the group for the long-term so that we can enjoy the benefits of a strong economy and also adequately accommodate any reverses," he said."The most important contribution to performance will be growing the occupancy and increasing rental rates in the existing platform of stores."Big Yellow increased its dividend for the year to 21.7p from 16.4p.Big Yellow shares were up 4.04% to 682.00p at 08:46 on Tuesday.