Insert quarterly data in monthly table

Question

Hello.

I have a table with monthly data (first two columns) in which I need to fill in the quarterly data from the last column, as shown in column three. 

Is there a way to copy the data from the right column and spread it in the right places in column three, or can I add two empty rows in between every two quarterly data rows from columns four and five, without having to do this for every row one by one, (to make them align with the monthly data rows)? 

The data is in different spreadsheets, or I can put them in the same sheet.

Thank you.

       Monthly data                                                     Quarterly data

Jan-48	51.7	6.01%		Jan-48	6.01%
Feb-48	50.2			Apr-48	6.68%
Mar-48	43.3			Jul-48	2.25%
Apr-48	45.4	6.68%		Oct-48	0.41%
May-48	49.5			Jan-49	-5.35%
Jun-48	53.0			Apr-49	-1.33%
Jul-48	48.4	2.25%		Jul-49	4.47%
Aug-48	45.1			Oct-49	-3.53%
Sep-48	42.1			Jan-50	16.92%
Oct-48	47.2	0.41%		Apr-50	12.65%
Nov-48	42.4			Jul-50	16.34%
Dec-48	35.0			Oct-50	7.94%
Jan-49	32.9	?		Jan-51	5.59%
Feb-49	31.3			Apr-51	7.13%
Mar-49	34.5			Jul-51	8.50%
Apr-49	35.5	?		Oct-51	0.89%
May-49	32.6			Jan-52	4.30%
Jun-49	31.6			Apr-52	0.83%
Jul-49	39.0	?		Jul-52	2.93%
Aug-49	47.0			Oct-52	13.79%
Sep-49	52.3			Jan-53	7.65%
Oct-49	51.0			Apr-53	3.16%
Nov-49	51.0			Jul-53	-2.23%
Dec-49	57.3			Oct-53	-5.93%
Jan-50	59.1			Jan-54	-1.85%

Answer 1

Assuming your second table in sheet2, use following formula, format your column C in % -

=IFERROR(VLOOKUP(A2,Sheet2!A:B,2,0),"")

Answer 2

That worked great. thank you.

How about the possibility of inserting 2 or more empty rows between every two consecutive rows that contain data?