Our jackup fleet is primarily located in, given the 49 rigs primarily located and so on the more active basis, we’ve 12 rigs in Mexico, we have 15 rigs in the Middle East and we have eight jackups in the North Sea. We are again in the process of transforming the fleet into a much more premium capability through the investment of well over $5 billion which will add 8 new ultra-deepwater drillships and 6 high specification jackups. 8 of those ships have already been delivered and there are five that remain in the yard.
Our current contract backlog stands at over $40.5 billion and extends through the end of decade extends out in to the year 2023. Our fleet expansion is driving industry-leading earnings and cash flow growth and we believe that provides real opportunities for shareholders moving forward. Our revenue backlog as measured by firm contracts represents the second largest backlog among drillers. Again it was a little over $40.5 billion at the end of first quarter of March 31 st 2012. And we expect this number to build as we see continued improvement in fleet activity, just general fleet activity as we had contracts for our remaining fleet and we also expect to see the backlog expand and grow as we add contracts for our ultra-deepwater drillships that are uncommitted, the three uncommitted ships and the five uncommitted jack ups.
So we have opportunities for the backlog to actually expand a good bit. The only jackup of the of the six that has contract. We recently announced a contract on the first at Noble Regina Allen for 18 months of $230,000 a day in the North Sea. This backlog provides great earnings visibility for us again. I said it went through into 2023, gives us a good visibility of the future which helps in planning, but it gives us a lot of diversity and a lot of flexibility in moving forward with the investment program.