v 1.6

1. Compress the size of data

v 1.5

1. Update the Electricity demand data set
2. Update the SAtemp data set 

v 1.4

1. Update the JCGS reference

v 1.3

1. add the European Central Bank yield curve data 
2. add the Federal Reserve interest rate data

v 1.2

1. update the read.hmd function
2. add the hmdstatistic and hmdcountry functions

v 1.1

1. remove some data sets
2. add the read.hmd function