The pressure exerted by a 3000 m column of water on the bottom layer is

P = $\mathrm{h\rho g}$ 

   = $3000 \mathrm{m} \times 100 \mathrm{kg} {\mathrm{m}}^{-3}\times 10 {\mathrm{ms}}^{-2}$

Fractional compression $\frac{∆\mathrm{V}}{\mathrm{V}} \mathrm{is}$

$\frac{∆V}{V} = \frac{P}{B} = \frac{3\times {10}^7 N{m}^{-2}}{2.2\times {10}^9 N{m}^{-2}} = 1.36\times {10}^{-2} = 1.36\%$