44. As shown in the figure, on the graph of the inverse proportion function $y=\frac{2}{x}(x>0)$, there are points $P_{1}, P_{2}, P_{3}, P_{4}$, whose x-coordinates are $1,2,3,4$ respectively. Perpendicular lines to the x-axis and y-axis are drawn through these points, and the areas of the shaded parts from left to right in the figure are $S_{1}, S_{2}, S_{3}$, respectively. Then $S_{1}+S_{2}+S_{3}=$ $\qquad$ .
answer: 1.5