Our second quarter 2021 earnings per share increased 17.5% compared to the second quarter of 2020.
Included in the results is a $0.03 per share benefit from weather primarily in the Northeast, where we saw a moderate impact from warmer and drier-than-normal conditions.
In the first six months of 2021, we invested $782 million with the majority dedicated to needed infrastructure improvements to better serve our customers.
As a reminder, we previously announced an O&M efficiency target of 30.4% by 2025.
We've added approximately 11,200 customer connections to date through closed acquisitions and organic growth and look forward to welcoming an additional 86,900 customer connections through pending acquisitions.
We plan to spend $1.9 billion in 2021 and about $10.4 billion over the next five years.
With a strong first half of 2021 and continued execution of our strategies, we're affirming today our 2021 earnings guidance range of $4.18 to $4.28 per share.
We're also affirming our long-term earnings per share compound annual growth rate range of 7% to 10%.
On June 28, the Iowa Utilities Board issued an order approving an increase in annual base revenue of $1 million for Iowa American Water.
The company's investment of almost $87 million in water system improvements was the primary driver behind the rate adjustment request.
As you've likely heard, Governor Newsom expanded the state's drought emergency declaration in 50 out of 58 counties.
Once we provide that information and staff deems the application complete, by statute, the Coastal Commission would have 180 days to process it.
In Missouri, the governor signed the Water and Sewer Infrastructure Act, which will become effective on August 28, 2021.
It also increases the cap from 10% to 15% of Missouri American Water's revenue requirement for these eligible projects.
The proposed bipartisan package supported by the administration includes $55 billion for water infrastructure.
For the 12-month period ending June 30, 2021, our O&M efficiency ratio was 33.9% compared to 34.3% for the 12-month period ended June 30, 2020.
During that period, we've added approximately 333,000 customer connections while expenses only increased at a compound annual growth rate of just over 1%.
We've announced multiple acquisitions in the first half of 2021, including our largest acquisition in York, Pennsylvania, which will add an equivalent customer connection total of more than 45,000.
As I mentioned earlier, so far in 2021, we've closed on eight acquisitions in four different states, adding approximately 3,000 new customer connections.
We've also added approximately 8,200 customer connections to organic growth in the first six months.
We look forward to adding another 86,900 customer connections through 37 currently signed agreements in eight states.
Second quarter 2021 earnings were $1.14 per share compared to $0.97 per share in the second quarter of 2020.
As Walter mentioned, included in earnings is an estimated $0.03 per share favorable impact from weather, primarily in the Northeast, where we saw conditions warmer and drier than normal through the quarter.
Results for the Regulated Business segment were $1.18 per share, an increase of $0.21 per share compared to 2020 earnings.
Results for the market-based business were $0.11 per share, a decrease of $0.02 per share.
And finally, parent company results decreased $0.02 per share in the second quarter of 2021 as compared to the same period last year.
Our 2021 earnings through June 30 were $1.87 per share, an increase of $0.22 per share compared to the same period last year.
Results for the six-month period include the estimated $0.03 per share favorable impact from weather in the second quarter of '21.
Regulated business results increased $0.27 per share compared to 2020 earnings, and our market-based business results decreased $0.05 per share and parent company results were unchanged year-over-year.
As I noted earlier, regulated results increased $0.21 per share.
And we saw a $0.30 per share increase in revenues from new rates in effect from acquisitions and from the lower demand in the second quarter of 2020 from the COVID-19 pandemic.
Also, as I mentioned previously, results reflect an estimated $0.03 per share increase from warmer and drier-than-normal weather, primarily in the Northeast.
Partially offsetting these results, O&M expense increased by $0.09 per share and depreciation expense increased $0.03 per share in support of growth in the regulated business.
The Market-Based Business results decreased $0.02 per share in the second quarter of '21 as compared to the second quarter of 2020.
The parent results decreased $0.02 per share in the second quarter of '21 compared to the second quarter of 2020, largely driven by higher interest expense to support regulated growth.
Consolidated results increased $0.22 per share for the year-to-date period compared to the same period last year.
Results for the regulated operations increased $0.27 per share for the year-to-date period.
We saw a $0.50 per share increase from additional revenue -- additional authorized revenue from acquisitions and from the lower demand in the second quarter of '20 attributable to the pandemic.
Year-to-date results also reflect the estimated $0.03 per share favorable weather benefit.
Offsetting these increases were increases in O&M expense of $0.18 per share and depreciation of $0.08 per share, all as a result of growth in the business.
The Market-Based Businesses results decreased $0.05 per share due to higher claims in 2021 in Homeowner Services Group, including the extreme cold weather across the country during the first quarter of '21, primarily in Texas and Illinois.
And to date, the regulated business has received $146 million in annualized new revenues in 2021.
This includes $100 million from general rate cases and step increases, excluding the agreed reduction in revenue from the amortization of excess accumulated deferred income taxes and $46 million from infrastructure surcharges.
We have also filed requests and are awaiting final orders on the two rate cases previously mentioned by Walter and two infrastructure surcharge proceedings for a total annualized revenue request of $71 million.
The company successfully completed a $1.1 billion debt offering in support of our $10.4 billion five-year capital plan and to refinance approximately $327 million of high coupon debt.
We issued $550 million each of 10- and 30-year debt with coupon rates of 2.3% and 3.25%, respectively.
I'd like to reiterate Walter's comments earlier because of our strong performance and continued focus on execution, we are affirming our 2021 earnings guidance range of $4.18 to $4.28 per share.
We are also affirming our long-term earnings per share, compound annual growth rate of 7% to 10%.
And as you can see on this slide, measured currently, we have delivered a total shareholder return of 126% over the last five years, outpacing our peers in the Philadelphia Utility Index as well as the S&P 500 Index.
As we've discussed previously, since 2007 through year-end 2020, we've reduced our greenhouse gas emissions by approximately 36%.
This means we're close to our goal of a 40% reduction by 2025.

Summary:
With a strong first half of 2021 and continued execution of our strategies, we're affirming today our 2021 earnings guidance range of $4.18 to $4.28 per share.
Second quarter 2021 earnings were $1.14 per share compared to $0.97 per share in the second quarter of 2020.
I'd like to reiterate Walter's comments earlier because of our strong performance and continued focus on execution, we are affirming our 2021 earnings guidance range of $4.18 to $4.28 per share.