Combining [m;2] matrices of histogram data where values of m vary

My experience with Matlab is very limited, and any help is greatly appreciated.

I have histogram data for occurrences of various processes at different time increments. For example:

[time increments;occurrences]

[0 1 2 3;23 58 81 32] [2 3 4 5 6;15 56 91 72 5] [1 2 3 4;2 105 42 29]

I need to build a single matrix like this:

[time increments;occurrences;occurrences;occurrences]

[0 1 2 3 4 5 6;23 58 81 32 0 0 0;0 0 15 56 91 72 5;0 2 105 42 29 0 0]

I have read how to combine simple matrices, but I'm having trouble figuring out how to insert the zero values for time increments were there is no data. If it matters, the two column matrices have approximately 100,000 rows.