For example, we diverted a minimum of 90% of waste from landfills at more than 140 of our global facilities, increasing our global diversion rate to roughly 85% from about 70% last year.
Even more impressive, at year end, 50 of our global facilities had achieved zero waste to landfill status.
Our overall global primary product line was strong and benefited sales by almost 3% versus the prior year.
Global steel drum volume fell by 1.5% per day versus the prior year.
GIP's fourth quarter adjusted EBITDA rose by roughly $47 million due to higher sales, partially offset by higher raw material, manufacturing, and transportation costs.
The business also benefited from a $3 million dollar FX tailwind.
Profits will be lower as the unprecedented run-up in steel costs provided a roughly $100 million tailwind to GIP's fiscal 2021 results that will not recur.
Paper packaging's fourth quarter sales rose by roughly $120 million versus the prior year due to stronger volumes and higher published containerboard and boxboard prices.
Adjusted EBITDA rose by roughly $10 million versus the prior year due to higher sales that were substantially offset by higher raw material, manufacturing, and transportation costs, including a significant $50 million -- $51 million drag from higher OCC index cost and an $8 million natural gas cost spike not contemplated in our guidance.
The business benefited from a $4 million legal settlement tailwind reported in SG&A that will not recur.
Fourth quarter volumes in our CorrChoice sheet feeder system were up 2.4% today versus the prior year.
Fourth quarter tube and core volumes were up 7% per day versus the prior year.
Fourth quarter net sales, excluding the impact of foreign exchange, rose 35% versus the prior year quarter due to stronger volumes and higher selling prices.
Adjusted EBITDA rose by 57 million, including a 7 million combined tailwind from FX and a one-time legal settlement.
Keep in mind our adjusted EBITDA result overcame an OCC index headwind of 51 million and roughly 40 million of non volume related transportation and manufacturing inflation, including an $8 million unforecasted natural gas cost spike.
Interest expense fell by 9 million versus the prior-year quarter due to lower debt balances.
Our fourth quarter GAAP and non-GAAP tax rate were both roughly 11%.
Fourth quarter adjusted Class A earnings per share more than doubled to $1.93 a share.
For fiscal '21, we delivered adjusted Class A earnings per share of $5.60 a share, a 74% improvement versus the prior year and a significant beat relative to our Q3 guidance.
Part of the earnings improvement came from a lower-than-anticipated non-GAAP tax rate of 18.1%, which benefited from reserve releases due to audit settlements, and statute of limitation expirations.
We estimate the lower tax rate relative to the guidance we shared at $0.15 at -- to fiscal '21 results.
Fourth quarter adjusted free cash fell roughly $79 million versus the prior year.
That said, our team is controlling what it can with strong results and trailing 12-month average working capital as a percentage of sales, improved by a significant 140 basis points to a -- year over year to 10.8%.
We anticipate spending between 150 million and 170 million in capital expenditures in fiscal '22 and target growing our dividend in '22 as mentioned in previous calls.
At the midpoint, we anticipate generating $6.15 of adjusted Class A earnings per share in '22.
Interest expense will be significantly lower in fiscal '22 as a result of our aggressive de-leveraging, and we expect it to evolve further when we move to refinance our 6.5% 27 senior notes sometime in the first half of calendar '22.
We anticipate '22 adjusted free cash flow between 400 million and 460 million.
It was a $222 million use in '21 as raw material cost inflation accelerated.
As an example, assuming a historic free cash flow of 11% in the midpoint of our '22 free cash flow guidance would imply a combined market cap of roughly $3.9 billion, or an increase of roughly 30%.
Adjusted EBITDA earnings per share has gone from $2.18 to $5.60 with no stock repurchases.
And adjusted free cash flow, which was $70 million in 2015 has averaged nearly $30 million in the last three years and will exceed $400 million in '22.

Summary:
Fourth quarter adjusted Class A earnings per share more than doubled to $1.93 a share.
We anticipate '22 adjusted free cash flow between 400 million and 460 million.