How do I use cut to separate by multiple whitespace?

I have this input, which is displayed in columns. I would like to get the second last column with the numbers of this sample: [ 3] 1.0- 2.0 sec 1.00 MBytes 8.39 Mbits/sec [ 3] 2.0- 3.0 sec 768 KBytes 6.29 Mbits/sec [ 3] 3.0- 4.0 sec 512 KBytes 4.19 Mbits/sec [ 3] 4.0- 5.0 sec 256 KBytes 2.10 Mbits/sec ... If I use cut -d\ -f 13 I get Mbits/sec 6.29 4.19 2.10 because sometimes there are additional spaces in between.