How do I smooth zoom just a spreadsheet to any increment?

Numbers has a Zoom box in the tool bar but the amounts are fixed. I'd like to choose ANY increment of zooming my spreadsheet. And, hopefully in a way which is smooth such as scrolling rather than entering or clicking something.

To be clear, I do NOT want to zoom my entire desktop screen and the windows on it. I do not want to magnify one small section. Enlarging the letters grossly affects the layout. If I use the corner handle to make the spreadsheet larger or smaller, it affects the layout. Ideally I'd like a FREE FLOWING way to enlarge or shrink the view of the specific spreadsheet. If I'm stuck entering numbers, that would be better than rigid choices.

I have an iMac 27-inch late 2009, OS X Yosemite (10.11.3)

Numbers Version 3.6.1 (2566)

Any help would be be appreciated. Thanks.